Banter between good friends is normal and harmless, but Keith Richards has been forced to apologise to Rolling Stones bandmate Mick Jagger when he took it a step too far by suggesting the singer get a vasectomy after becoming a father for the eighth time at 73.

Mick Jagger performing live with the Rolling StonesMick Jagger performing live with the Rolling Stones

It's certainly not an unpopular opinion that Mick is perhaps 'too old' to have had yet another child, but it's one that you'd expect his closest friends to keep to themselves. As outspoken as ever though, 74-year-old Keith wasn't about to keep his silence.

'Mick's a randy old b*****d', he told WSJ Magazine. 'It's time for the snip-you can't be a father at that age. Those poor kids!'

Now, however, the guitarist wishes he never said anything about Mick's fatherhood choices given that it is rather a sensitive issue when his youngest child is just 14-months-old.

'I deeply regret the comments I made about Mick in the WSJ which were completely out of line', he told Page Six in a statement. 'I have of course apologized to him in person.'

Mick's son Deveraux Octavian Basil Jagger, with girlfriend Melanie Hamrick, was born in December 2016. He also has an 18-year-old son named Lucas Maurice with Brazilian model Luciana Gimenez Morad; 20-year-old Gabriel Luke Beauregard, 26-year-old Georgia May, 32-year-old James Leroy Augustin and 33-year-old Elizabeth Scarlett with Jerry Hall; 46-year-old Jade Sheena Jezebel with Bianca Jagger; and 47-year-old Karis with Marsha Hunt.

It's probably not the first time Keith has had to apologise to Mick for making comments about him that were a little out of line. Indeed, there has always been ups and downs in their friendship, as he well-documented in his autobiography 'Life'.

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'Mick and I would have spats anyway, no matter what I said in the book, and I left a lot out', he said. 'Mick and I live off of this fire between us. It's been up and downhill, but if I'm talking about the Rolling Stones, there ain't a frontman like Jagger. Don't matter how many bones you want to pick out of him, he's amazing to work with.'